The Best Thermostat Setting for a Desert Summer

The U.S. Department of Energy suggests about 78 degrees when you are home and need cooling, and a higher setting when you are away. That is a reasonable starting point in Indio for healthy adults. For older adults, infants or anyone with a health condition, comfort and safety come first, and a lower setting may be appropriate. Avoid turning the system off completely on hot days; raise the setting a few degrees instead.

In a mild climate, turning the AC off while you are out can save energy. In Indio, the house can absorb a great deal of heat on a 110-degree afternoon, and the system then has to remove it all during the hottest hours, often during the most expensive part of the day. A moderate setting held steady, with a few degrees higher when you are away, is usually gentler on the equipment and the bill.

A completely hot house is also hard on electronics, food, medications and anything stored in a garage that shares air with the home.

The Imperial Irrigation District has encouraged customers to move heavy electricity use out of the 4 to 9 p.m. peak, including through an optional Time-of-Use rate. If you are on that kind of rate, pre-cooling helps: let the system bring the house a couple of degrees cooler before 4 p.m., then raise the setting slightly during the peak. The house coasts on the stored cooling.

This works best in well-insulated, shaded homes. In an older house with poor insulation, the stored cooling disappears quickly, and comfort may suffer. Watch how your home behaves before committing to a schedule.

A programmable or smart thermostat makes a steady schedule easy. Many smart models let you check the indoor temperature from a phone, adjust it remotely and receive an alert if the house gets too hot, which is useful for seasonal residents and for families checking on older relatives. IID has offered instant rebates on smart thermostats through its online Power Store.

If you install a new thermostat on a heat pump, make sure it is configured for heat pump operation. A wrong setting can make the system heat when it should cool. Our page on heat pump repair covers that and other heat pump issues.

In cooling mode, Auto is usually the better choice. With the fan on Auto, it stops when the compressor stops, letting moisture drain off the indoor coil. With the fan always on, some of that moisture can be blown back into the house, and the fan uses more electricity.

If the house never reaches a reasonable setting even in the evening, the problem is the system, not the thermostat. A dirty coil, a low charge or a failing part may be limiting capacity. A spring AC tune-up catches many of these before summer.

A thermostat on a sunny wall, near a lamp, above a kitchen appliance or close to a supply vent reads the wrong temperature and makes the system run too much or too little. If one room is always much warmer or cooler than the thermostat suggests, its location may be part of the problem. A technician can tell you whether moving it, or adding a remote sensor on some smart models, would help.

Also check that the thermostat is level and clean if it is an older mechanical model, and that batteries in battery-powered models are fresh before summer starts.

The best setting is the one that keeps your household safe and comfortable while letting the system work steadily rather than in bursts. Start near 78, adjust for the people in your home, and use pre-cooling if your rate rewards it. For every service, see AC repair Indio.